The use of tubular textile fabrics for soft-tissue implantable prostheses is well known in the repair or replacement of damaged or diseased lumens in the body. For example, tubular devices or conduits are used to repair lumens such as in the esophagus and colon areas, and, in particular, prostheses are used in the vascular system to repair, buttress or replace a weakened section of the vessel. Such conduits are generally affixed in a specified location in the vessel by means of sutures, stents, hooks or other mechanisms which serve to secure the device in place.
Synthetic vascular grafts for the repair or replacement of blood vessels have taken a wide variety of configurations and shapes. The most common type of vascular graft is that manufactured in a generally tubular form extending along a longitudinal axis. Such tubular vascular grafts are particularly well suited for use in end-to-end anastomoses, i.e., where the damaged portion of the blood vessel is dissected and the ends of the tubular graft are connected to the cut ends of the blood vessel to span the dissected portion. These tubular grafts may also be used in end-to-side anastomoses, i.e., where the end of a graft tube is typically attached to the side of a blood vessel. Such tubular vascular grafts are also useful in percutaneous applications, where the graft is inserted percutaneously and is positioned to span a damaged or diseased portion of a blood vessel without dissection.
Various designs have been proposed in order to provide for proper suturing and proper internal blood flow with end-to-end as well as end-to-side vascular grafts. For example, U.S. Pat. No. 5,156,619 discloses a flanged end-to-side vascular graft which is provided in the form of a tubular vascular graft having a flared end portion. Such a graft is cannibalized, i.e., cut, from a conventional bifurcated graft structure which includes a main tubular section and two smaller branched tubular sections. The bifurcated graft is cut along an arcuate segment at the bifurcated arch between the bifurcated tubular sections and along the wall of the main tubular section, to provide a single tubular graft with a flanged end formed from the arcuate cut. The flanged end, however, typically requires stitching along the flanged portion, since bifurcated textile grafts of the prior art typically require suturing at the bifurcated portion in order to be blood-tight. Further, as the flanged graft in the '619 patent is constructed of only a single tube with a flange at one end, it is designed to be attached to an end of a blood vessel, and is not suitable for repair or replacement of a branched section of a blood vessel. Still further, the graft disclosed in the '619 patent is designed to extend from the blood vessel at a gradually sloping angle, and would not be appropriate for applications where an end-to-side graft is required which incorporates a branch extending substantially perpendicular to a main tubular section.
Occasionally, it is necessary to provide an end-to-side vascular graft in which the side branch portion extends substantially perpendicular from the main portion to replace a portion of a blood vessel or to be positioned within a portion of a vessel which splits into one or more branch vessels. In order to overcome the deficiencies of earlier end-to-side grafts which do not include a generally perpendicular extending branch, true end-to-side vascular grafts have been constructed with branch portions which extend generally perpendicular to the main tubular section. Such end-to-side vascular grafts have typically been constructed by suturing one tubular vascular graft to the side of a second tubular vascular graft. Such end-to-side vascular grafts are used, for example, to repair or replace a damaged or diseased portion of the aorta. In such procedures, an aortic vascular prosthesis which includes a main aortic trunk portion and arterial branch portions extending generally perpendicular to the main aortic trunk portion for the left and right carotid arteries and the subclavian artery is particularly well suited. In order to provide an aortic vascular prosthesis with three branches, a surgeon will typically suture three separate straight tubular vascular grafts to the side of a larger tubular graft. Such suturing, however, usually occurs immediately prior to or during a procedure, is labor intensive and requires extreme skill and precision in suturing, thereby introducing the potential for human error.
Prior art end-to-side vascular grafts such as the aforementioned aortic vascular prostheses have not been completely successful. In particular, the attachment of one tubular graft to the side of another tubular graft results in a sharp transition, typically with an immediate transition of 90.degree. from the main tubular section to the branched tubular section. Additionally, such attachment results in suturing or stitching directly at the point of transition between the main tubular section and the branched tubular section. Such sharp transitioning and suturing at this transition result in poor blood flow through the transitional portion, and can lead to an undesirable thrombosis at the transition.
Alternatively, custom-made aortic vascular prostheses can be constructed. While these custom-made structures may overcome some of the aforementioned deficiencies, they are extremely expensive and time-consuming to fabricate.
Accordingly, there is a need for a vascular graft which is useful in repair or replacement of a branched section of a blood vessel which is substantially blood-tight and includes a gradual transition from the main lumen to the branched lumen, and which does not include any suturing directly at the lumen transition.